Development of new methods for demonstration of early chemical and structural alterations of fibrous proteins. Reactive dyes, neutral premetallized dyes, textile auxiliaries and iodinated dyes will be employed. Fluorescence microscopy: Studies of infrared fluorescence of arterial lesions will be continued. Long-wave exciting light will be used studies of stained alpha-helical and collagenous proteins. The usefulness of polarized fluorescence for demonstration of early arterial lesions will be explored. New fluorescent brightening agents will be tested. Polarization microscopic studies of stained connective tissue fibers and myofibrils in cardiovascular lesions will be continued. Studies of arterial lesions in children and young adults: In order to minimize observer bias studies of all age groups will be carried out "blind". Emphasis will be on the nature of early chemical and conformational changes and the sequence of these alterations. New technics developed during the year will be applied to current studies and to completed cases where indicated. Observations will be correlated with data on age, sex, race and clinical history, especially family history of cardiovascular diseases.